1. Field of the Invention
The present invention relates generally to ink cartridges. In particular, the present invention is directed towards ink cartridges which may be used in combination with printers.
2. Description of Related Art
Ink cartridges which are configured to be used in combination with ink jet printers are known in the art. In such known ink cartridges, it is possible to detect when the amount of ink in the ink cartridge is relatively low. For example, one known ink cartridge comprises a movable member which is pivotally supported inside an ink reservoir. The movable member has a blocking portion at one end and a float portion at the other end. When the ink reservoir is filled with ink, the rotation of the movable member due to the rising of the float portion in the vertical direction is restricted by a stopper, such that the blocking portion is positioned at the blocking position, where the blocking portion may block light emitted from an ink jet printer. When the surface level of the ink is lowered, the position of the float in the vertical direction also is lowered, and the position of the blocking portion in the vertical direction rises, thereby moving the blocking portion from the blocking position to a non-blocking position. Thus, the printer then may determine that the ink cartridge includes substantially no ink, and the ink cartridge needs to be replaced.
Nevertheless, if the ink cartridge vibrates when the printer is transported with the ink cartridge installed, or the like, ink bubbles may form inside the ink reservoir. When bubbles form inside the ink reservoir, the rotation of the movable member may be hindered by the surface tension of bubbles adhering to the inner wall surface of the ink reservoir, such that an out-of-ink state may be detected when there is sufficient ink within the ink reservoir. Moreover, it may take several hours for the bubbles to sufficiently disappear, such that the movable member accurately may rotate in accordance with the amount of ink within the ink reservoir.